# -----------------------------------------------------------------------
# Copyright: 2010-2022, imec Vision Lab, University of Antwerp
#            2013-2022, CWI, Amsterdam
#
# Contact: astra@astra-toolbox.com
# Website: http://www.astra-toolbox.com/
#
# This file is part of the ASTRA Toolbox.
#
#
# The ASTRA Toolbox is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# The ASTRA Toolbox is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with the ASTRA Toolbox. If not, see <http://www.gnu.org/licenses/>.
#
# -----------------------------------------------------------------------

import astra
import numpy as np


vol_geom = astra.create_vol_geom(64, 64, 64)

# There are two main 3d projection geometry types: cone beam and parallel beam.
# Each has a regular variant, and a 'vec' variant.
# The 'vec' variants are completely free in the placement of source/detector,
# while the regular variants assume circular trajectories around the z-axis.

# -------------
# Parallel beam
# -------------

# Circular

# Parameters: width of detector column, height of detector row, #rows, #columns
angles = np.linspace(0, 2*np.pi, 48, False)
proj_geom = astra.create_proj_geom('parallel3d', 1.0, 1.0, 32, 64, angles)

# Free

# We generate the same geometry as the circular one above.
vectors = np.zeros((len(angles), 12))
for i in range(len(angles)):
    # ray direction
    vectors[i, 0] = np.sin(angles[i])
    vectors[i, 1] = -np.cos(angles[i])
    vectors[i, 2] = 0

    # center of detector
    vectors[i, 3:6] = 0

    # vector from detector pixel (0,0) to (0,1)
    vectors[i, 6] = np.cos(angles[i])
    vectors[i, 7] = np.sin(angles[i])
    vectors[i, 8] = 0

    # vector from detector pixel (0,0) to (1,0)
    vectors[i, 9] = 0
    vectors[i, 10] = 0
    vectors[i, 11] = 1

# Parameters: #rows, #columns, vectors
proj_geom = astra.create_proj_geom('parallel3d_vec', 32, 64, vectors)

# ----------
# Cone beam
# ----------

# Circular

# Parameters: width of detector column, height of detector row, #rows, #columns,
#             angles, distance source-origin, distance origin-detector
angles = np.linspace(0, 2 * np.pi, 48, False)
proj_geom = astra.create_proj_geom('cone', 1.0, 1.0, 32, 64, angles, 1000, 0)

# Free

vectors = np.zeros((len(angles), 12))
for i in range(len(angles)):
    # source
    vectors[i, 0] = np.sin(angles[i]) * 1000
    vectors[i, 1] = -np.cos(angles[i]) * 1000
    vectors[i, 2] = 0

    # center of detector
    vectors[i, 3:6] = 0

    # vector from detector pixel (0,0) to (0,1)
    vectors[i, 6] = np.cos(angles[i])
    vectors[i, 7] = np.sin(angles[i])
    vectors[i, 8] = 0

    # vector from detector pixel (0,0) to (1,0)
    vectors[i, 9] = 0
    vectors[i, 10] = 0
    vectors[i, 11] = 1

# Parameters: #rows, #columns, vectors
proj_geom = astra.create_proj_geom('cone_vec', 32, 64, vectors)
